1. Field of the Invention
The invention relates to a folding assembly in a rotary printing machine with guide rollers and feed rollers for transporting a printing-material web.
2. Description of the Related Art
German reference DE 31 28 430 C2 has already disclosed a web-fed rotary printing machine in which a printing-material web is drawn in from a web-infeed unit and runs through a plurality of printing units one after the other for printing on both sides of the web. After passing through the printing units, the printing-material web that has been made wet by the printing ink is dried in a dryer. After being dried, the printing-material web is cooled in a cooling unit and fed, via a folder superstructure, to a folding unit, in which it is cut and folded in the conventional manner.
It has been found that the printing-material web has a tendency to assume the temperature of the ambient air surrounding it, or at least approach this temperature, as it is fed from the cooling unit to the folding unit. Because of the machinery running in printshops, which are generally insufficiently temperature-conditioned if at all, temperatures may reach above 30.degree. C. Because of the above tendency of the printing-material web to at least approach the ambient temperatures, these elevated temperature conditions may result in the printing-material web likewise assuming temperatures above 30.degree. C. If the printing ink, for example a so-called heat-set ink, assumes a temperature of 30.degree. C. or above after leaving the dryer and the cooling unit, particles of the printing ink soften again. This, in turn, results in smearing of the printing ink on elements of the folding assembly and of the folding unit. The softening of the ink also may cause the products produced from the printing-material web, which are to be stacked, to stick to one another, which considerably adversely affects the printing quality.